I recently downloaded and installed SQL Server 2017 on my laptop and I am having trouble connecting excel with said server. I have tried a variety of trouble shooting options (TCP/IP enabled, checking that browser is active, named pipes is enabled, shared memory enabled, making sure that outside connections are allowed in Microsoft Excel, etc.) and every time I receive one of the following messages: error 40 or error 26. I even adjusted the string and made sure my instance and server name were correct (NE-SF-T******\\SQLSERVER and ".....\\mssqlserver) and I am still running into the same error. Any help on this would be appreciated.

How are you trying to connect? If you installed SQL using default instance, then you only need to specify your hostname, without instance name. See screenshots attached, my hostname is called SQL2017 so I'm connecting to it with no issues.

If you still have issues, either disable firewall or open 1433 and 4022 TCP ports.

Open Windows Firewall with Advanced Security

Right click Inbound Rules and select New rule

In the New Inbound Rule Wizard window make the following modifications:

Thanks for responding. So I turned windows firewall off, allowed a special rule for the port and the server and I am still receiving the same error message. Would it happen to be a security issue on the excel side? I allowed all connections under excel..

Yes I am able to connect. The only thing that I can not do is connect my excel (externally) to the database so that I can import files into an excel document. See the attachment. I have already enabled pipes and TCP/IP connections.

Can you please send a screenshot of the login screen from your SQL Management Studio? I just want to see server type you're connecting to and server name.Afterwards, please detail step by step what you're doing in Excel, how you are trying to connect to SQL. Again, screenshots will be helpful.

So I go to Get Data---SQL Server---Input servername\instance name (I have tried all formats including "/" and "//." and "\\." and "\") then I log in with my windows credentials. Would creating or setting up a mixed log in mode solve that issue? See the screenshots..